autofs: remove possibly misleading /* #define DEBUG */

Having this in autofs_i.h gives illusion that uncommenting this enables
pr_debug(), but it doesn't enable all the pr_debug() in autofs because
inclusion order matters.

XFS has the same DEBUG macro in its core header fs/xfs/xfs.h, however XFS
seems to have a rule to include this prior to other XFS headers as well as
kernel headers.  This is not the case with autofs, and DEBUG could be
enabled via Makefile, so autofs should just get rid of this comment to
make the code less confusing.  It's a comment, so there is literally no
functional difference.

Link: http://lkml.kernel.org/r/20160831033409.9910.77067.stgit@pluto.themaw.net


Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>